1. Technical Field
The present invention relates generally to a stator of an electric rotating machine to be mounted in for example, automotive vehicles and a production method thereof.
2. Background Art
Japanese Patent First Publication No. 2004-32882 (corresponding to U.S. Pat. No. 6,833,648 B2, assigned to the same assignee as that of this application) discloses a stator winding which extends through slots formed in a stator core. The stator winding is made up of a plurality of U-shaped conductor segments. Each of the conductor segments has two legs inserted into two of the slots of the stator core. Ends of the legs of each of the U-shaped conductor segments extend outside the slots. The ends of the legs of one of the U-shaped conductor segments are welded to those of another of the U-shaped conductor segments to make the stator winding.
The ends of the legs of the U-shaped conductor segments, as described above, extend outside the slots to make a first coil end lying on one of opposed end surfaces of the stator core in a circumferential direction of the stator core. Each of the U-shaped conductor segments has a head also called a turn portion) connecting between the legs. The heads of the U-shaped conductor segments are arrayed outside the other of the end surfaces of the stator core to make a second coil end extending in the circumferential direction of the stator core. Portions of the legs of each of the U-shaped conductor segments are disposed in the slots of the stator core and will also be referred to as in-slot portions below.
The above type of stator winding in which the ends of the conductor segments are welded together outside the end surface of the stator core needs to separate the ends from one another to ensure a required degree of electrical insulation therebetween. To this end, the ends of the legs of the conductor segments extending outside the end surface of the stator core may be, as illustrated in FIG. 5, bent outward. Specifically the ends of some of the conductor segments 31A have bends 32A oriented outward in a radal direction of the stator core 20A.
Of the ten ends (i.e., five pairs to be welded) of the legs of the conductor segments 31A, two which are located most radially inward of the stator core 20A extend straight upward without any bends. The eight remaining ends have the outward bends 32A. The more the ends of the conductor segments 31A are located outward of the stator core 20A, the greater the size of the bends 32A. It is, therefore, necessary to extend the outward bend 32A of one of the conductor segments 31A which is located most outwardly of the stator core 20A in the radial direction thereof far away from the end surface 22A of the stator core 20A. This results in an increase in axial height h2 of the outward bend 32A from the end surface 22A of the stator core 20A, which leads to an increase in entire axial height H2 of the first coil end 35A made up of the ends of the conductor segments 31A.